It's not the same, 3D requires specific hardware that you had to go out of your way to use.
3D requires a 3D player and 3D Television
4K requires a 4K player and 4K Television
The only thing extra 3D needs is your 3D Glasses.
Compare that to 4K Televisions, which in the UK are no more pricey than that of the HD Standard Televisions, and the same will happen with the 4K Blu-ray players in due time.
But 8K televisions are dropping in price and will soon be no more pricey too. If you have no skin in the game, and you are shopping for a TV, what will you buy? 4K or the better 8K? And then would you want 4K or 8K movies to maximize the use of your TV?
4K & 3D are false equivalences.
I was only equating to their niche status, and eventual demise. Samsung pulled out of the 3D player market. Now Samsung pulled out of the 4K player market.
If they saw the futures growing, they wouldn't have pulled out from either. But Samsung sees the writing on the wall unfortunately.